Finished QCX

Work has kept me stupidly busy this year… the only project completed is a build of the QCX kit from QRP labs (and a new trapped antenna for the MTR). Built for 80m to complement the 40/30/20 MTR3b and provide a morning NVIS option.

The case was custom build out of 1mm Al using a home made brake and follows the design of the LNR Precision MTR case. 

Sensitivity seems fine and puts out 3.8W on 80M on initial measurements. Now I’m only missing an antenna…

Arthur’s Seat VK3/VC-031

I’ve driven up Arthur’s Seat a few times, run up it more than a few times, and driven past it even more often. Still hadn’t got around to activating the thing…

I rarely take part in the VHF field days as a proper contestant, but I often use it to test out my 23cm station. I’m also keen to reward those who put the effort in and head out with decent stations. If I remember, I usually try to give out a few contacts, mostly on the higher bands.

Arthur’s Seat has a good takeoff to the south, west, and north depending on where you set up so, despite the trees, is not a bad place for UHF/Microwave work. Especially nice are the numerous picnic tables.

I was headed down the peninsula to meet up with some other members of our astronomical society and had just enough time to squeeze a single band activation in on 23cm.

The easy and smart way to do 23cm is to liaise on a lower band to establish beam headings, but there is a particular joy in getting random QSOs on this band. My 10el Yagi has a very broad beamwidth anyway.

Because I had no intention on entering the contest, I put a spot up on sotawatch. About 10 minutes of calling later I was rewarded with a QSO with Andy VK3VKT, followed by VK3ER/P in/near the wombat state forest, and VK3BCU. No regular SOTA chasers, likely due to the hour and lack of alert. I could have qualified the summit in 30 seconds if I put the 2m rubber ducky on the 817, but I would have been there for another half an hour working the hordes… the weather was pretty miserable with a freezing southerly wind.

Not successfully qualified, but 3 more 23cm contacts, summit activated, and an Andrew 2 Andrew. What’s not to like? Longest was 113km with VK3ER/P.

Only 15 minutes or so late for the meeting.

New Years Rollover

The lucky SOTA addicts in VK (and now ZL and JA) have UTC rollover during a reasonable time period:  11am EAST. This means double activator points can be claimed so many have headed to the hills on the 1st of Jan, and usually to high value summits. Thus far I had managed to miss all this fun.

With a couple of days in Albany, a 50 minute drive south of the Stirling Ranges in WA, I had the chance to finally take part. The only catch was that rollover is at 8am in VK6. 

Having chosen Toolbrunup Peak VK6/SW-004 and working the numbers back, I figured an 5am start would see me on the summit safely in time to qualify both sides of rollover. I last climbed this one 18 years prior with a group of University friends. It’s a 2km climb to the summit.
An uneventful drive after 4 hours of sleep saw me arriving at a packed! car park. One couple had camped overnight on the saddle and had just walked down, several other groups were heading up.

A quick  breakfast at the car and I was off. Don’t be fooled by the easy section here, which I might add I fell on during the descent… 

Through the scree field: 
With nice views poking through (not the summit): 
  and then you get to this:

 You’re rocking hopping and climbing the rest of the way to the summit. Almost no one I saw climbing, including myself, had boots. I used my trail runners which offer excellent grip but no ankle support and others used even lighter running shoes. Provided you have strong ankles and good proprioception a light shoe is not necessarily a bad choice here. 

The second boulder field with a trail marker:  
 One exiting the boulder field the path veers to the right through thick squipole unfriendly scrub to emerge at the base of the final climb.  
 The path is marked but not particularly well. Last time we deliberately chose a route further to the right which offered a nice section of climbing. The normal path however offers enough fun, especially with heavy pack:

None of it is particularly exposed however.

And finally up the top which as I remembered is a jumble of giant boulders:

  A leisurely setup allowing me to catch my breath and I was on air at 7:36am, my spotted time, having burnt all my 30minutes margin on the climb. The rocks did offer the best shack I have ever operated from (which was on the western side of the summit):

As i was about to check 14.310 I found John VK6NU on Mt Randell doing the same enabling a quick S2S to get the ball rolling. 5 minutes later I had qualified the summit, I think a record time for me in VK6 including S2S’s with Matt VK1MA on VK1/AC-008, Andrew VK1AD on VK1/AC-043, Gerard VK2IO on VK2/HU-093 and initiated a S2S with JS1UEH/1 on CW which crossed the UTC boundary. I believe the reports were exchanged in 2016 and have logged it as such. My first JA chase and S2S.

In 2017 I also worked Glenn VK3YY and John VK2YW on CW, reworks of the other S2S’s and picked up Phil VK6QS ON nearby Mount Hassell VK6/SW-009, Peter VK3ZPF on VK3/VC-005, Allen VK3ARH on VK3/VS-027, Tony VK3CAT on VK3/VC-037 and Andrew VK3ARR on Mt Buller VK3/VE-008.

There were a bunch of other chasers including Tom VK5EE, Nev VK5WG and Rick VK4RF.

Phil VK6QS was on my backup summit, within 2km LOS and we both managed to clobber each other. I eventually gave up with a s7 noise floor (the phase noise of the 817 LO?) when both in the SSB segment, and let him work the chasers.

Trying 15m CW, I had a call from steve VK7CW with good signals but he couldn’t hear me, and almost completed a QSO with JJ1SWI which would have completed JA for me but he faded before I got my report.

In general weak signals, and many I couldn’t hear. Tony Vk3CAT was an easy copy on CW, but not a trace on SSB. Good signals as always into VK5. All completed QSO’s were on 20m at 50W.

I did try 40m SSB but couldn’t find and hold a frequency due to DX QRM.  

Plenty of reptile life on the summit with a whole family of lizzards coming out to sunbath, including right where I was sitting. I’ll have to dig out a photo from the SLR.

Name that SOTA peak, several in there…

During the descent I did fall on an easier section of track landing heavily on my right wrist trying to arrest my further slide. It became rather swollen and bruised and I ended up having to drive out one handed. A week later and I’ve got most of the use back. It just shows that you can’t relax for a second on most of this track. Ankles were also fairly tired from the walking on uneven/unstable surfaces. I’m a bit out of shape…

Not bad day out despite the early start. I even got to practice some rusty Deutsch with no fewer than 5 of the others being German! 

Frustratingly I ended up on 995 chaser points…  would have been the perfect summit to reach Shacksloth on!


Family of lizards. 4 in the first image, found two more in the uncropped image. Saw probably a dozen in total.  


Squid pole bag

I spent 2 hours on my sisters sewing machine to make a bag for the 7m squid pole that will be more flexible in mounting arrangements on backpacks, especially my 30L day pack. None of the squid pole bags seem to ever have loops.

Designed also to allow the pole to sit below the pack a bit.   

Made from 210D nylon (same as the pack I believe), webbing and fixtures from Tiergear. My sewing skills after almost 30 years leave something to be desired, but as a first effort/prototype it will do. Still need to trim threads etc.

Leg clearance is almost right, probably should put the pole slightly higher.


The edging was a major pain, couldn’t easily pin it with what I had on hand so it got out of place a few times! 
Now to see if it’s strong enough. I suspect it will outlive the pole. At least the top cap for the pole will stop falling out.

Now to build one for the short & light travel pole, which will work with ice axe loops on many packs

Final Plugin filters

The latest Minikits order arrived today with the final high voltage capacitors and toroids:  

Left to right: 80m, 40m, 30/20m.

Plots of the 80m and 40m filters:  

The cutoff for the 40m filter is a little tight but it should be fine. The 80m filter showed slightly better stop band attenuation when touching the ground of the input but I suspect this is connector related. More than adequate in any case.

Now onto that SWR meter board…

VK3/VC-037 and antenna tuning

I’ve known about this summit since Tony VK3CAT activated late last year and it looked like an easy one to get. Wanting to test out the amplifier and tune my ground plane it seemed a good choice for an afternoon activation. Unfortunately the forecast was for heavy rain starting from the afternoon, however by 2pm it was obvious this was mostly hanging to the west and only slowly approaching.

Following Glenn VK3YY’s as usual excellent directions I arrived just before the alerted time and setup. As it was a drive up, the laptop and scalar analyzer came with me and the following was produced initially:

Antenna was right at the bottom of the band edge which is what I remembered. After a bit of trimming I got the following (uncalibrated so off by 15dB or so):

1.5 swr across the band,  1.2 in the middle, much more suited for SSB operation in the upper half. Not too shabby. The radials will receive some attention next time.

Putting the 817 and amp on and things were very strange with a pronounced lack of band noise on 20m after I started. However I did manage to work S58AL,VK4FE, VK8GM, ZL1BYZ and ZL1TZW on 20 with good reports received but I struggled at times hearing the other side. When I switched off the amp after the last station the band noise immediately rose and a lightbulb lit up. The LED I added was drawing current through the relay coil so was preventing the RX/TX relay from releasing the contacts. Doh. Test activation well and truly justified, I never picked that up on the bench. 

Announcing I was listening on 144.150 I pulled down the ground plane and put the EFHW up for 40M. Contacts followed on 40m with VK2YK, VK5PAS, VK2FENG, VK5IS and VK2IO/M. No contacts made on 2m probably due to the last minute notice.

During this some rain arrived but not enough to pull the bothy bag out, I just covered the rig and relied on the waterproof paper of the logbook.

Leaving at 6:10 after a short second guess of my route, I was home by 7:30. Most of the drive was in heavy rain with plenty of water on the road in places. Well timed indeed.

Not a bad little summit, easy to get to, room for antennas, squidpole supports, a very scenic drive there and I qualified it with a 40 or 50dB attenuator on receive! Apologies to those who could hear this alligator but could not be heard themselves.

W6JL amp v1.1

My amp had an initial outing in a not totally finished configuration, several things were missing. 

In short:

  • Added a bicolor ON/TX led
  • Made the filters pluggable


20M LPF. Capacitors are 630v SMD.

The 20M filter shows enough attenuation by 20MHz to also be usable on 30M as expected and tests confirm this.

Done just in time for some small summit to summit party…

Only thing remaining is the SWR/display board.

40m LPF analysis

My W6JL amp didn’t seem to quite meet the spurious emissions limits in Australia with the 2nd harmonic a few dB short of 50dB down, though this was at the limits of my test equipment. This was a bit of a mystery as a 5 element LPF should have easiy taken care of the remaining 2nd harmonic.

Using the scalar analyzer neatly reveals why:

That little kink around 12Mhz is worth  5dB or so and so explains the gap.

The filters are being rebuilt as 7 element pluggable units and with hopefully better construction this will be the end of that.


Measuring the new 20m LPF i became suspicious of the results and it turns out the buffer amp in the analyzer is not ideal and is being affected by the load. 

Remeasured filter but with a 6dB attenuator after the amp:

Looks perfect.

I’ve now convinced myself that what i’m seeing of the 2nd harmonic is actually artifacts of the test setup. In any case, I’m moving to higher order LPF anyway.

Rebuilt the antenna analyzer as a scalar network analyzer

Some time back I built the k6bez antenna analyzer which utilized a cheap eBay DDS and and resistive bridge. It served it’s purpose though accuracy was questionable with no compensation of the diode voltage drop and lacking in power. My build being cheap and nasty lacked a case so it was fragile.

With an pressing need to build and tune some filters and wanting to put the thing in a box, it seemed like a good idea to rebuild it but as a Simple Scalar Network Analyzer allowing for more flexibility in measurements. I just happened to have a couple of AD8307 log detectors in the junk box having snapped them up at a good price a while back. The enclosures were also really well priced on eBay.

I’m fairly happy the way it turned out.   

I’ve set the amp so output power is 0dBm. The AD8307 log power detector is in a soon to be covered shielded enclosure, buffer amp below and the blue box contains a return loss bridge, thereby getting me back to where I started.  

The calibration results don’t seem too bad. The roll off at the lower end is likely due to either the 0.01uF cap on the detector input or the use of 43 material for the toroid in the bridge. It will do until the solar activity forces us onto 160m… Testing with a variety of different non-50ohm loads results in the expected return losses within fractions of a dB. The AD8307 is worth the cost.

Back to multibanding the skimmer and the hf amp…

Mt Sheridan VK4/NT-175

A family holiday to Port Douglas meant a chance to activate a new association. The superficial attractiveness of the NT region for SOTA is mitigated by the fact that most of the summits are in tropical rainforest. In the time Vk4 has been live, only 2 summits have been activated in NT.

A detailed searched revealed a few possible candidates, mostly around Cairns. One, Trintity Beach, had already been activated, but I found two that are mostly drive up and worth more. There were a couple of 10 pointers that might be  doable around Port Douglas but some research by Matt Vk1MA and his local connections helped eliminate these as easy time efficient options. Critical family holiday friendly attributes.

Anyway, VK4/NT-175 was picked as it had well detailed walking notes as it’s enroute to a well known, but apparently infrequently visited, lookout. In SOTA it’s known as Cairns 2, but the local name appears to be Mt Sheridan. 

Anyway, exiting highway 91 on Lake Morris Drive, take note of the odometer and just before 10km there is a hairpin with a grassy clearing where one can park. The below is looking back to where to you drive from.

Note that this road is a clearly marked cycling training ground and while I saw no insane people climbing at 3pm, it was quite busy at 5pm with both cyclists and walkers, so I suggest driving up in the heat of the day. The road is extremely narrow and windy, with several single lane sections. Expect to average 30km/h up. It would be fantastic on any form of bike, motorized or not.

On the way up I passed a sign marking the start of Dinden National Park confirming this would also count as vkff 0675. I was 99% sure before this was the case. Not that I actively participate in Parks, but useful for others. I will submit the log.

The access track to the comms facility on top is obvious just around the bend. Squidpole unfriendly gate included.

 It’s a 800m walk to the top but don’t fool yourself into thinking it’s that easy. It’s steep and you’ll likely  be climbing in 30degree heat with 90% humidity. Enough to get the heart racing and sweat pouring.

Part way up the nicely formed gravel track will fork. Correct choice is the  option on the left. The other leads to a dead end after quite a way.  

The summit:    

Running slightly late due to the need to stop and double check the map and turning right on the walk instead of left I was somewhat behind but quickly setup along the track. No problems and one would have enough space to put up an 80m antenna provided you can clear vegetation as no squidpole supports exist clear of it.

 Rig used was FT817 at 5w. Calling on 40m was fruitless, so switched to 20m where I had a nice stream of callers. I heard a reference to another parks station on 7.144, so qsyd there to try to work vk4ffab. Despite many tries and him being 59 to me, I was unheard. I did manage to pick up Fred Vk4FE in nearby Port Douglas though, and we had a decent chat. Fred had helped earlier with information regarding one of the other Summits and propagation. I may still get to Trinity Beach.

So 1 hour ten minutes of operation yielded 10 qso’s on 20m and 1 on 40m, all VK. I did change antennas and tried 15m for 10minutes but no luck. I was suffering high swr and no ATU. I really do need to tune that antenna. Like in VK6 and E5, a lot of CQing with silence and then a flurry of activity.

Given the propagation outlook with a geoeffecive coronal hole, things worked out quite well however QSB was wild and Europeans were reporting auroral effects. I was disappointed to have to shutdown as 20m was wide open to the US, but I had to be home in time for dinner. No time for dx cw. Dinner mission accomplished however.